Safety device for rubber mills



Oct. 5, 1948. J. E. LODGE 2,450,760

SAFETY DEVICE FORiRUBBEB MILLS Filed Nov. 19, 1946 2 Sheets-Sheet 1 24 I so |-2 I INVENTOR F/a/ JE-LODGE' I By ATTORNEY v Oct. 5, 1948. J. E. LODGE SAFETY DEVICE FOR RUBBER MILLS 2 Sheets-Sheet 2 Filed Nov. 19. 1945 INVENTOR .15. LODGE By if TTORNEY Patent ed Oct. 5, 1948 SAFETY DEVICE FOR RUBBER MILLS Joseph E. Lodge, Baltimore, Md., asslgnor to Western Electric Company, Incorporated, New York, N. Y., a corporation of New York Application November 19, 1946, Serial No. 710,785

This invention relates to safety devices and more particularly to safety devices for mills, such as rubber mills.

In processing compounds containing plastic material, such as rubber, a synthetic rubber-like material or a thermoplastic material, the compounds often are worked in mills to work the compounds and to mix the ingredients thereof.

Occasionally, operators of such mills have their hands and arms drawn into such mills and serious injuries result. Various types of safety devices have been used with varying degrees of success in attempts to prevent such injuries. However, such deyicesusually are placed out of the working area of the mill and require deliberate movement of an operator caught in the mill to stop the mill. Sometimes, with safety devices of the prior art, accidents occur so quickly that there is no time for an operator in danger to deliberately actuate the device to stop the mill before his hand is caught and already damaged.

An object of the invention is to provide new and improved safety devices.

A further object of the invention is to provide new and improved safety devices which are actuated by involuntary actions of operators of rubber mills and the like to stop the mills when the operators are in danger of having their hands caught in the mills.

A safety device illustrative of the invention includes a, bar positioned in front of a rubber mill in a position in front of and slightly higher than the normal orbits of the knees of an operator of the mill. The bar is movable upwardly .and toward the mill to stop the mill when an operator gets caught in the mill and unconsciously moves his legs against the rod in an effort to pull himself free of the mill.

A complete understanding of the invention may be obtained from the following detailed description of a safety device forming a specific embodiment thereof, when read in conjunction with the appended drawings, in which:

Fig. 1 is a fragmentary, front elevation of a rubber mill equipped with safety devices forming embodiments of the invention;

Fig. 2 is a fragmentary, vertical section taken along line 2--2 of Fig. 1;

Fig. 3 is an enlarged, fragmentary, vertical section showing a portion of the apparatus shown in Fig. 2, and

Fig. 4 is a diagrammatic view of an electrical control circuit associated with the safety devices.

Referring now in detail to the drawings, a mill l (Fig. 2) includes a pair of mill rolls l2 and 5 Claims. (of. 18--2;)

l4 driven by an electric motor I8 (Fig. 4) in clockwise and counterclockwise directions. respectively, as viewed in Fig. 2. A receiving pan if is positioned below the mill rolls to receive the material falling between the rolls in the carlystages of milling a batch of the material. The pan I1 is long enough to permit the material to be drawn between it and either of the mill rolls so that the material may be moved to the tops of the rolls to rework it. A pair of safety devices l8 and 20 forming specific embodiments of the invention are positioned at opposite ends of the receiving pan so that they do not interfere with such materialhandling operations.

The safety devices it! and 20 are identical in construction and principle of operation, and are positioned on both sides of the mill so that an operator 22 may safely work on either side of the 4 mill. Since the safety devices i8 and 20 are alike,

only the one designated l8 will be described in detail.

. The safety device l8 includes a tubular bar 23 fastened rigidly to arms 24 and 26 mounted pivotally on brackets 28 and 30 secured to standards 32 and 34, respectively, of the mill Ill. The ends of the bar project through guide slots, of which a guide slot 36 (Fig. 2) is shown, formed in guides 38 and 40 secured rigidly to the standards 32 and 34, respectively. The bar 23 normally rests in the position shown in full lines in Fig. 3, but is moved upwardly and to the right to the position shown, in broken lines in that figure when a leg 42 of the operator is moved forward as the operator instinctively crouches to pull himself loose when he feels one or both of his hands getting caught in material 44 being worked by the mill and being drawn toward the bite of the rolls l2 and I4.

As the bar 23 is moved from its full-line position to its broken-line position, a hook 50 formed on the arm 24 engages an arm 52 of a limit switch 54. As the hook 50 moves further, it moves the arm 52 from its full-line position, as seen in Fig. 3, to its broken-line position, as shown in Fig. 3. This movement of the arm 52 opens a normally closed contactor 56 (Fig. 4) of the switch 54, which breaks a, circuit through a holding relay winding 58 from a power line conductor 60 to a power line conductor 62. The relay winding 58 is energized by the power line conductors 60 and 62 during the normal operation of the mill through the following circuit: a holding contactor 64 in parallel with a normally open, manually operable starting switch 86, which holding contactor is held closed when the winding 58 is energized but opens when the winding 58 is deenergized, the contactor 58, a contactor 68 of the safety device 20, the relay winding 58 and a normally closed, manually operable stopping switch 10. Opening the circuit to the winding 58 deenergizes the winding 58 so that the contactor 64 opens to prevent reenergization of' the winding 58 when the switch 54 is reclosed without also momentarily closing the starting switch 66. The contactor 68 of the safety device 20 corresponds to the contactor 5G and acts in a similar mannerwhen the safety device 20 is actuated.

When the holding relay winding 58 is deenergized, contacts 12-12 in a power line ll to the motor I6 open to stop the motor is and thereby stop the mill rolls l2 and M (Fig. 2) before the operator's hands reach the bite of the rolls, therey preventing injury to them. The operator then may free his hands, move away from the safety device 18 so that the bar 23 and the hook 50 move back to their full-line positions and then restart the apparatus by momentarily closing the starting switch 66.

In the operation of the safety device l8, the bar 23 is suificiently close to the'mill roll l2 and is spaced low enough, just above knee-level of the operator, that the operator 22 does not contact the bar 23 during the normal operation of the mill. However, if an operator gets either one or both hands caught in the material 44 so that the material draws the caught hand toward the bite of the rolls l2 and M as they draw the material through the bite thereof, the operator instinctively crouches to throw his weight into a pull to withdraw his hand from the bite of the rolls. In so crouching, the knees of the operator are moved forward, and the portions of the thighs of the operator just above his knees actuate the safety device 18, thereby stopping the mill Ill before hishands have been insured. Also, if, when a hand is being caught. the operator moves one foot forward to get greater pulling power to tug his hand free, his leg will actuate the safety device II.

The fact that the bar 23 must be moved upwardly and inwardly to stop the mill prevents accidental stopping of the mill if the material happens to be dropped onto the bar, as in dropping the material in transferring the material from the pan I! to the top of the mill rolls l2 and H.

The above-described safety device 18 is positioned out of the way of both the operator and the material 44 in its location just in front of the mill roll I! and below the main portion of the mill roll so that it does not interfere in the slightest with normal movement of the operator and is not in the way of the material as it is handled. The fact that the safety device is operated by the instinctive movement of the operator trying to keep his hands from being drawn with the material into the bite of the rolls is time saving over devices which require deliberate action by the operator to actuate them, thereby lessening chances of injury to the hands. Also, the fact that the device is actuated by the legs of the operator permits the mill to be stopped by the operator even if both hands are being caught, which would not be possible in devices actuable only by a hand or an arm of the operator.

What is claimed is:

1. In a mill including a pair of mill rolls mounted at the same level and means including an electric motor for rotating the rolls. in inrunning directions such that the portions of the peripheries of the rolls nearest to each other move downward- 4 ly, a safety device which comprises a bar, a pair of arms pivotally mounted for mounting the bar in a position below the .centerline of and in front of one of the mill rolls at a level about that of the knees of an operator of the mill, said arms serving to permit the bar to be moved inwardly and upwardly toward the last-mentioned mill roll, and means associated with the bar including a limit switch operable by movement'of the bar for stopping the electric motor.

2. In a mill including a pair of mill rolls mounted at the same level and means for rotating the rolls in inrunning directions such that the portions of the peripheries of the rolls nearest to each other move downwardly, a safety device which comprises a bar, a pair of arms pivotally mounted for mounting the bar in a position below the centerline of and in front of one of the mill rolls, said arms serving to permit the bar to be moved inwardly and upwardly toward the lastmentioned mill roll, and means associated with the bar and operable by movement thereof for stopping the rotation of the rolls.

3. In a rubber mill including apair of mill rolls mounted at the same predetermined level, said level being such that the centerlines of the rolls are above the knees of an operator of the mill and means including an electric motor for rotating the rolls in inrunning directions, a safety device which comprises a pair of arms pivotally mounted at opposite ends of one of the mill rolls, a bar carried by the free ends of the arms, means for normally supporting the bar in a position in front of and slightly above the normal paths of movement of the knees of an operator so that the bar is struck when the operator crouches to tug himself free from the mill, said rod-supporting means serving to permit the bar to be moved upwardly and toward the last-mentioned roll when struck, a limit switch for stopping the electric motor, and an actuator movable by the bar for actuating the limit switch when the bar is moved upwardly and toward the last-mentioned roll, said bar-supporting means serving to normall hold the bar sufficiently far from the last-mentioned roll to permit a batch of material to be moved between the last-mentioned roll and the bar without contact therewith from a position below the mill rolls.

4. In a rubber mill including a pair of mill rolls mounted at the same predetermined level which is such that the centerlines of the rolls are above the knees of an operator of the mill and means for rotating the rolls in inrunning directions, a safety device which comprises a bar, means for supporting the bar in a position slightly above the knees Of an operator and below the centerline of and in front of one of the mill rolls and for guiding the bar inwardly and upwardly when the bar is struck by a knee of the operator, and means associated with the bar and operable by inward and upward movement thereof for stopping the rotation of the rolls.

5. In a rubber mill including a'pair of mill rolls mounted at the same predetermined level which is such that the centerlines of the rolls are above the knees of an operator of the mill and means for rotating the rolls in inrunning directions, a safety device which comprises a bar, a pair of pivotally mounted arms mounting the bar for arcuate movement, a pair of plates having arcuate guide slots therein for supporting the bar in a position below the centerline of and in front of one of the mill rolls at a level slightly above that of the knees of an operator of the mill and for guiding the bar inwardly and upwardly toward the last-mentioned mill roll when the bar 15 UNITED STATES PA'I'ENTS struck by a knee of the operator, and means as- Number e Date sociated with the bar and operable by inward and 4 .105 'I'hropp Feb. 27, 1923 upward movement thereof for stopping the rota- 5 44 Perkins et a1 June 1934 171011 of the rolls. P

JOSEPH E. LODGE. Number Country Date REFERENCES CITED 453,367 Great Britain Sept. 10, 1936 The following references are of record in the m file of this patent: 

